1. Your 600 dealer, they must have the infamous INEX stamp.
2. The only one you can use is the B&S pump, p/n 808656. Available from your 600 dealer or B&S.
3. Any steel bodied filter
4. The only one you can use is from B&S, p/n 692084. Available from your 600 dealer or B&S
5. An allen wrench and feeler gauge. I don't remember what size allen wrench, sorry.
6. I get NGK plugs from my 600 dealer.